Means for supporting an inner membranous vessel of a low temperature liquefied gas tank of a membrane type

ABSTRACT

Means for supporting an inner membranous vessel of a low temperature liquified gas tank of a membrane type including an outer vessel of a pressure resisting structure, a heat insulating layer provided at the inside of the outer vessel and the inner membranous vessel provided further at the inside of the heat insulating layer, said inner vessel being formed as a bag having a flat bottom portion and side wall portions connected to said bottom portion via curved edge portions, comprising an annular reinforcing member provided at an upper edge portion of said bag, a plurality of suspension means slidably passing through a roof portion of the outer vessel, and a plurality of counter-weight means provided at the outside of the outer vessel, said suspension means each being connected with said annular reinforcing member at one end thereof and connected with one of said counter-weight means at the other end thereof, whereby the counter-weight means are isolated from the low temperature of the low temperature liquified gases resulting in a low manufacturing cost of the tank as well as are readily exposed for inspection regardless of loading or unloading of the tank.

United States Patent 1 Yamamoto [451 Jan. 21-, 1975 MEMBRANOUS VESSEL OF A LOW TEMPERATURE LIQUEFIED GAS TANK OF A MEMBRANE TYPE Inventor: Katsuro Yamamoto, Tokyo, Japan 73 Assignee: Bridgestone Liquefied Gas Company, Ltd., Tokyo, Japan 22 Filed: Nov. 15, 1972 Appl. No.: 306,581

[30] Foreign Application Priority Data Nov.-24, 1971 Japan 46-94212 [52] US. Cl 220/9 LG, 220/15 [51] Int. Cl B65d 7/22 [58] Field of Search, 220/9 LG, 10, 15, 26 R, 220/26 S, 88 B; 114/74 A [56] References Cited UNITED STATES PATENTS 2,050,686 8/1936 Wiggins...- 220/26 R 2,408,539 10/1946 Wiggins ....'220/26 R 2,944,452 8/1961 Morris0n-.... 220/9 LG 3,085,708 4/1963 Dosker 220/9 LG 3,101,861 8/1963 Mearns et a1 220/10 3,158,459 ll/1964 Guilhem 220/15 3,267,685 8/1966 Schroeder 220/9 LG 3,352,443 11/ 1967 Sattelberg et al. 2 2 0 9 I G 3,570,700 3/1971 Yamamoto et al. 220/10 11/1971 Yamamoto 220/9 LG 3,712,500 l/1973 Marchaj 220/9 LG Primary ExaminerWilliam 1. Price 7 Assistant ExaminerStephen Marcus Attorney, Agent, or Firm-Stewart and Kolasch, Ltd.

[57] ABSTRACT Means for. supporting an inner membranous vessel of a low temperature liquified gas tank of a membrane type including an outer vessel of apressure resisting structure, a heat insulating layer provided at the inside of the outer vessel and-the inner membranous vessel provided further at the inside of the heat insulatinglayer, said inner vessel being formed as a bag having a flat bottom portion and side wall portions connected to said bottom'portion via curvededge portions, comprising an annular reinforcing member provided at an upper edge portion of said bag, a plurality of suspension means slidably passing through a roof portion of the outer vessel, and a plurality of counter-weight means provided at the outside of the outer vessel, said suspension means each being connected with said annular reinforcing member at one end thereof and connected with one of saidv counter weight means at the other end thereof, whereby the counter-weight means are isolated from the low temperature of the low temperature liquified gases resulting in a low manufacturing cost of the tank as well as are readily exposed for inspection regardless of loading or unloading of the tank.

MEANS FOR SUPPORTING AN INNER v MEMBRANOUS VESSEL OF A LOW TEMPERATURE LIQUEFIED GAS TANK OF A MEMBRANE TYPE BACKGROUND OF THE INVENTION 1. Field of the'lnvention This invention relates to a means for supporting an inner membranous vessel of a tank for, storing low temperature liquefied gases such as methane, oxygen, ammonia, propane, etc., which are in a gaseous state at room temperature and are liquefied by being cooled down beyond their boiling points under atmospheric pressure.

2. Descriptionof the Prior Art Conventionally, a tank of this kind comprises an outer vessel of a pressure resisting structure, a heat insulating layer provided at the inside of the outer vessel and an inner membraneous vessel provided further at the inside of the heat insulating layer, said inner vessel being formed of a thin plate and adapted to be readily expanded by the internal pressure applied by the liquefied gases loaded therein to come in close contact with the inside surface of the heat insulating layer, whereby the internal pressure is transmitted to theouter vessel via the heat insulating layer to be supported by the outer vessel.

In the tank of the abovementioned membranous structure, since the inner vessel can not stand by itself, it is suspended at its upper portions or clamped by bolts so that it does not fall down due to its own gravity. However, the inner vessel makes complicated deformationswhen it goes through various conditions from a room temperature unloaded condition to a low temperature loaded condition via a low temperature unloaded conditionor vice versa, and therefore, it is unfavorable to give a restriction to the inner vessel such as to preventtheabovementioneddeformations, because stress concentrations will be caused by giving such a restriction.- v v Therefore, the inner vessel must be so constituted as .to be able to make deformations according to the con- .must be made ofexpensive-low temperature resisting materials and at the same time results in a complicated structure, whereby there is a drawback that the overall manufacturing cost of the tank is unfavorably increased. p

Furthermore, since the abovementioned conventional suspension mechanism is mounted at the inside roof portion of the outer vessel, there is a restriction of the space available for the provision of the suspension mechanism, and therefore, it is difficult to provide the suspension mechanism in a size large enough to satisfactorily accomplish its operation. Or otherwise, if a suspension mechanism having a high or perfect performance is to beprovided, the overall volume of the tank is increased, resulting in an unfavorable increase of the overall manufacturing cost of the tank.

If the suspension mechanism for the inner vessel has gone wrong, there is a danger that the mechanism restricts deformations of the inner vessel and as a result causes breakage of the inner vessel. Therefore, it is desirable that the suspension mechanism is in such a condition that the operation thereof can always be checked. In this connection, if the suspension mechanism is provided at the inside of the outer vessel, there is a drawback that the mechanism can not be readily checked of its operation.

SUMMARY OF THE INVENTION Therefore, it is the object of this invention to solve the abovementioned problems in the conventional means for supporting the inner membranous vessel and to provide an improved means for supporting the inner membranous vessel of a low temperature liquefied gas tank of a membrane type including an outer-vessel of a pressure resisting structure, a heat insulating layer provided at the inside of the outer vessel and the inner membranous vessel provided further at the inside of the heat insulating layer, said inner vessel being formed as a bag having a flat bottom portion and side wall portions connected to said bottom portion via curved edge portions. g

The abovementioned object is accomplished, according to this invention, by such a means that comprises an annular reinforcing member provided at an upper edge portion of said bag, a plurality of suspension means slidably passing through a roof portion of the outer vessel, and a plurality of counterweight means provided at the outside of the outer vessel, ,said suspension means each being connected with said annular reinforcing member at one end thereof and connected with one of said counter-weight means at the other end thereof. 1

The inner membranous vessel formed 'as a bag having a flat bottom portion and side wall portions connected to said bottom portion via curved edge portions can be readily deformed to come in uniform and closecontact with the inside surface of the heat insulating layer under the application of an internal hydraulic pressure when'it has been properly'susp'ended at its upper edge portion where it is reinforced by an annular reinforcing member. In this case, the upperedge portion of the inner vessel is supported by such suspension means that are slidably passing through an upper wall or roof portion of the outer vessel and are supported at their upper ends bycounter-weight means which can provide a substantiallyconstant and stable suspension force ad-- justed to hold the innermembranous vessel in a most favorably self-standing condition such, that there is caused no over-stressing due to an over-suspension or no buckling of theinner. membranous vessel due to an roof portion of the tank is simplified and it is avoided that the volume of the outer vessel is increased for housing the counter-weight means.

By providing proper gas seal means at the portions where the suspension means pass through the wall of the outer vessel, it is possible to sufficiently keep the gas-tightness of the outer vessel.

Since in this case the gas seal means is provided at the outside of the outer vessel where it is almost at atmospheric temperature, sealing means made of inexpensive common materials and having a simple structure can be employed.

BRIEF DESCRIPTION OF THE DRAWING The accompanying drawing is a partial view of a tank shown in a vertical section, wherein the means for supporting an inner membranous vessel according to this invention is incorporated as an embodiment thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, the tank herein shown has an outer vessel 1 of a pressure resisting structure, a heat insulating layer 2 of a compression resisting structure provided at the inside of the outer vessel and an inner vessel 3 of a membranous structure made ofa thin plate of a low temperature resisting material such as nickel steel, stainless steel or aluminum. The inner membranous vessel 3 is formed as a bag having a flat bottom portion 3a and side wall portions 3b connected to the bottom portion via curved edge portions 3c. The side wall portions 3b of the inner vessel are extending upward until the upper ends thereof reach a level adjacent the upper ends of the side wall portions of the heat insulating layer 2 or the joining portions of side wall portions la and roof portion lb of the outer vessel.

The heat insulating layer 2 may be formed of a heat insulating material having by itself compression resisting characteristics such as hard polyurethane foam or may be formed of an assembled structure including, for example, wooden frames, the spaces left therein being filled with pulverized pearlite so that the assembled structure has compression resisting characteristics as a whole. However, roof portion 2a of the heat insulating layer 2 may be made of heat insulating materials having no compression resisting characteristics such as glass wool or polyurethane, since the roof portion does not subject to any substantial load.

The upper end portion of the inner vessel 3 is reinforced by an annular reinforcing member 4 firmly fixed thereto. Upon the roof portion of the outer vessel 1, there are mounted a plurality of poles 5 (only one of which is shown in the drawing). The pole 5 has a pivot bearing 6 at its upper end, where a lever 7 is pivotally mounted. At one end of the lever 7 .is connected a suspension means 8 such as a wire, which is extending downward through a pipe P mounted to penetrate the roof portion lb of the outer vessel androof portion 2a of the heat insulating layer and adapted to provide a passage for suspension means. The lower end of the suspension means is connected to the annular reinforcing member 4 fixed to the inner vessel. At the other end of the lever 7, there is provided a weight 9 acting as a counter-weight for suspending the inner vessel 3 via the suspension means 8 from falling down due to its own gravity. In this case, the weight 9 is adjusted to provide such a suspension force that can hold the inner membranous vessel in a self-standing condition with no over-stressing due to an over-suspension but with no danger of causing buckling due to an insufficient suspension, while allowing relatively free deformations of the inner membranous vessel to avoid stress concentration.

Over a proper extent of the suspension means located above the upper end of the pipe P, there is provided a flexible seal member 10 such as a bellows made of a synthetic rubber to keep the gastightness of the outer vessel while allowing free movement of the suspension means through the pipe P according to the expansion or contraction of the inner vessel due to changes of temperature and/or load.

The counter-weight mechanism comprising the pole 5, pivot bearing 6, lever 7, weight 9, etc. is housed in a trunk 11 closed with a cover plate 12 to be protected from the weather. The counter-weight mechanism can be exposed for inspection any time when required by removing the cover plate 12, even when the tank is filled with low temperature liquefied gases without opening the inside of the tank to the atmosphere. The inside space of the trunk 11 may be filled with inert gases such as nitrogen for the purpose of safety.

As an alternative method of keeping gas-tightness at the portion where the suspension means 8 passes through the pipe P, in a manner of not constantly sealing the pipe, the space confined by the trunk 11 and the cover plate 12 may be kept gas-tight. In this case, when the counter-weight mechanism is to be inspected, the passage in the pipe P is first closed from outside via a proper remote control means, and then the evaporated gases filling the space in the trunk 11 are replaced by inert gases, before the cover plate 12 is removed.

I claim:

1. A device for supporting an inner membranous vessel of a low temperature liquefied gas tank of the mem-- brane type including an outer vessel having a pressureresisting structure, said outer vessel provided with a roof portion, a heat insulating layer provided at the inside of the outer vessel and the inner membranous vessel provided inside of the heat insulating layer, said inner vessel being formed as a bag having a flat bottom portion and side wall portions which are connected to said bottom portion by curved edge portions, said device for supporting the inner membranous vessel comprising an annular reinforcing member provided at an upper edge portion of said bag, a plurality of suspension means slidably passing through the roof portion of the outer vessel, and a plurality of counter-weight means, each being housed in a trunk containing a cover plate and provided at the outside of the outer vessel, each of saidsuspension means being connected at one end thereof with said annular reinforcing member and at the other end thereof with one of said counterweight means.

2. The device according to claim 1, wherein a flexible seal member is provided at the portion where said suspension means passes through the outer vessel.

3. The device according to claim 1, wherein the space confined by the trunk and the cover plate is filled with inert gases.

4. A device for supporting an inner membranous vessel of a low temperature liquefied gas tank of the membrane type including an outer vessel having a pressureresisting structure, said outer vessel provided with a roof portion, a heat insulating layer provided at the inside of the outer vessel and the inner membranous vessel provided inside of the heat insulating layer, said inner vessel being formed as a bag which substantially conforms to the inside surface of .the heat insulating layer, said device for supporting the inner membranous vessel comprising 'an annular reinforcing member provided at the upperedge portion of said bag, and a plurality of suspension systems housed in a trunk containing a cover plate and provided at the roof portion ofthe and the other end of the lever being connected to the counterweight.

6. The device of claim 5, wherein the suspension means is a wire.

7.. The devoce of claim 5, wherein a flexible seal member is provided at that portion of the suspension system where the suspension means passes through the outer vessel.

8. The device of claim 7, wherein a pipe extends through the roof portion of the outer vessel and the roof portion of the heat insulating layer to provide a passage for receiving the suspension means.

9. The device. of claim 8, wherein the flexible seal is a bellows made of a synthetic rubber to maintain the gas-tightness of the outer vessel while allowing free movement of the suspension means through the pipe according to the expansion. or contraction of the inner vessel due to changes in temperature and/orload. 

1. A device for supporting an inner membranous vessel of a low temperature liquefied gas tank of the membrane type including an outer vessel having a pressure-resisting structure, said outer vessel provided with a roof portion, a heat insulating layer provided at the inside of the outer vessel and the inner membranous vessel provided inside of the heat insulating layer, said inner vessel being formed as a bag having a flat bottom portion and side wall portions which are connected to said bottom portion by curved edge portions, said device for supporting the inner membranous vessel comprising an annular reinforcing member provided at an upper edge portion of said bag, a plurality of suspension means slidably passing through the roof portion of the outer vessel, and a plurality of counter-weight means, each being housed in a trunk containing a cover plate and provided at the outside of the outer vessel, each of said suspension means being connected at one end thereof with said annular reinforcing member and at the other end thereof with one of said counter-weight means.
 2. The device according to claim 1, wherein a flexible seal member is provided at the portion where said suspension means passes through the outer vessel.
 3. The device according to claim 1, wherein the space confined by the trunk and the cover plate is filled with inert gases.
 4. A device for supporting an inner membranous vessel of a low temperature liquefied gas tank of the membrane type including an outer vessel having a pressure-resisting structure, said outer vessel provided with a roof portion, a heat insulating layer provided at the inside of the outer vessel and the inner membranous vessel provided inside of the heat insulating layer, said inner vessel being formed as a bag which substantially conforms to the inside surface of the heat insulating layer, said device for supporting the inner membranous vessel comprising an annular reinforcing member provided at the upper edge portion of said bag, and a plurality of suspension systems housed in a trunk containing a cover plate and provided at the roof portion of the outer vessel, each of said suspension systems including a suspension means slidably passing through the roof portion of the outer vessel and a counter-weight means, said suspension means being connected at one end thereof with said annular reinforcing member and at the Other end thereof with the counter-weight means.
 5. The device of claim 4, wherein each of said suspension systems further includes a pole member containing a pivot bearing at its upper end and a lever means pivotally mounted to the pivot bearing, one end of the lever being connected to the suspension means and the other end of the lever being connected to the counter-weight.
 6. The device of claim 5, wherein the suspension means is a wire.
 7. The devoce of claim 5, wherein a flexible seal member is provided at that portion of the suspension system where the suspension means passes through the outer vessel.
 8. The device of claim 7, wherein a pipe extends through the roof portion of the outer vessel and the roof portion of the heat insulating layer to provide a passage for receiving the suspension means.
 9. The device of claim 8, wherein the flexible seal is a bellows made of a synthetic rubber to maintain the gas-tightness of the outer vessel while allowing free movement of the suspension means through the pipe according to the expansion or contraction of the inner vessel due to changes in temperature and/or load. 